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Topic: Is Continous Autofocus a big deal for those who shoot video (Read 30764 times)

The Canon XF100/105/300/305 are all marketed as "professional" camcorders. For $3000 to $8000, they certainly don't seem targeted at the kiddie's birthday party market. And all of them have autofocus capability, and it's apparently fairly sophisticated. (They also have built-in lenses and fairly small sensors.) If "professionals" use manual focus, why is this capability included in these models?

Those cameras have sensors the size of a bee's prick, relative to full frame\super 35\aps-c. Everything's basically in focus already.

I dont see why autofocus is such a big deal when these movie studios spending 100,000+ on cameras are still MANUALLY pulling focus. Professional studios don't use auto focus. People shouldn't rely on the software, rely on the trained eye instead.

I don't understand why this thread has gone on this long and people still aren't getting that AUTOFOCUS DOESN'T WORK on LARGE SENSORS OR FULL FRAME OR SUPER 35mm FILM. It never has, and while it might in the future, you almost certainly wouldn't want it to. People seem to be thinking like still photographers, or people who use camcorders with 2/3 inch or smaller sensors.

why would you even try that? Video at f/1.4 already has a razor-thin DOF, and all the videos I've seen that go to that level look horrible, because someone breathing makes their face go out of focus. You need a completely still scene and static shot to even go to that aperture.

Autofocus at f/1.4 would be a nightmare, it'd jump back and forth so much

why would you even try that? Video at f/1.4 already has a razor-thin DOF, and all the videos I've seen that go to that level look horrible, because someone breathing makes their face go out of focus. You need a completely still scene and static shot to even go to that aperture.

Autofocus at f/1.4 would be a nightmare, it'd jump back and forth so much

why would you even try that? Video at f/1.4 already has a razor-thin DOF, and all the videos I've seen that go to that level look horrible, because someone breathing makes their face go out of focus. You need a completely still scene and static shot to even go to that aperture.

Autofocus at f/1.4 would be a nightmare, it'd jump back and forth so much

First, I'm responding to another post, making the point that in low light, you're more likely to want to open the aperture (to get more light) which makes for a challenge in focusing accurately.

Second, dof doesn't just depend on aperture. Depending on subject distance and focal length, f/1.4 might not be too unmanageable. I've shot with a 20mm f/1.7 on a panasonic GF2 without too much difficulty (btw, it autofocuses smoothly)

I don't understand why this thread has gone on this long and people still aren't getting that AUTOFOCUS DOESN'T WORK on LARGE SENSORS OR FULL FRAME OR SUPER 35mm FILM. It never has, and while it might in the future, you almost certainly wouldn't want it to. People seem to be thinking like still photographers, or people who use camcorders with 2/3 inch or smaller sensors.

works reasonably well on micro 4/3. Touch screen makes it possible to "guide" the AF instead of requiring it to guess what you want to focus on. The AF doesn't seem as "jerky" as contrast AF in Canon/Nikon.

why would you even try that? Video at f/1.4 already has a razor-thin DOF, and all the videos I've seen that go to that level look horrible, because someone breathing makes their face go out of focus. You need a completely still scene and static shot to even go to that aperture.

Autofocus at f/1.4 would be a nightmare, it'd jump back and forth so much

I remember this vimeo clip interviewing Shane Hurlbut ACS. The camera man was shooting manually at F/1.4 which looked nice with the shallow depth of field. Unfortunately while Shane Hurlbut's upper body remained stationary, being passionate about cinematography he often becomes very animated with his hands. As a result the footage had this constant blurring from the motion of his hands and arms. Having autofocus wouldn't have solved this problem. Filming at a higher f-stop would have.

I was sort of surprised that while all the comments on the vimeo page were nothing but praise for the camera operator, not one person (besides myself) stopped to ask if he shouldn't have shot the video at a higher f-stop.

Then you're doing something wrong. At that point you should be providing your own light or get your subject to stay stationary. Autofocus is not the issue, it's the experience of the operator.

One doesn't always have the luxury of being able to make the light or subjects accomodate the equipment. Sometimes it's the other way around. Here's the kind of scenario I'm thinking of -- I'm filming something like a kid running around. I aren't going to shoot this with razor thin dof, but if I don't have a lot of light, I'm not going to shoot it at f/11 either. Manually focusing something like this is tricky.

Thing is, a dedicated video camcorder is gonna have issues handling that shot as well, if you are in dark enough light where you have to shoot at f/1.4 or f/1.8. I know my XA-10 ($2000 camcorder) could probably handle it, but, it would definitely have some noise, and even there the auto-focus isn't perfect. When I film classrooms, it guesses which kid to focus on and can miss focus in darker rooms.

It's always a compromise. I can't even take useable pictures on my XA-10...so its a big trade-off to get auto-focus that certainly isn't perfect.

Thing is, a dedicated video camcorder is gonna have issues handling that shot as well, if you are in dark enough light where you have to shoot at f/1.4 or f/1.8. I know my XA-10 ($2000 camcorder) could probably handle it, but, it would definitely have some noise, and even there the auto-focus isn't perfect. When I film classrooms, it guesses which kid to focus on and can miss focus in darker rooms.

It's always a compromise. I can't even take useable pictures on my XA-10...so its a big trade-off to get auto-focus that certainly isn't perfect.

Panasonic's micro 4/3 let you use the touch screen to guide the AF system -- you can basically choose the "AF point" and it moves smoothly to it like a manual focus pull.

I don't believe it isn't possible for a DSLR to have decent AF in video mode, but neither Canon nor Nikon have achieved this. Not clear to me whether Sony are any better.

The Canon XF100/105/300/305 are all marketed as "professional" camcorders. For $3000 to $8000, they certainly don't seem targeted at the kiddie's birthday party market. And all of them have autofocus capability, and it's apparently fairly sophisticated. (They also have built-in lenses and fairly small sensors.) If "professionals" use manual focus, why is this capability included in these models?

Because these cameras are not meant to be used in cinematic situations. Run and gun videography often means you need to have plenty of dof all the time, and manual focus is often impossible because you've got the cam on your shoulder and there's no way you can have a focus puller running alongside. You're too busy keeping the subject in frame and keeping track of your sound guy/cables/levels/keeping down the shake etc.

Shallow dof and manual focus is a different world. A controlled world where distance to subject is often measured with a laser before each take and the focus puller sits and twiddles back and forth between markings on his remote. Try that in the real world....

Comments about tiny sensors just don't have relevance in the world of video except on a set. After all, Full HD is only 2MB, you don't need much of a sensor for that. So many other issues are more important.

Shallow dof is SO cool right now. Just because DSLRs can be used for video. Gee, wow. Who gives a toss in the real world.